A331150 Triangle read by rows: T(n,k) (n>=k>=1) = f(n,n-k+1) where f(n,k) = floor((n/k)*ceiling(n/k)).

1, 1, 4, 1, 3, 9, 1, 2, 4, 16, 1, 2, 3, 7, 25, 1, 2, 3, 4, 9, 36, 1, 2, 2, 3, 7, 14, 49, 1, 2, 2, 3, 4, 8, 16, 64, 1, 2, 2, 3, 3, 6, 9, 22, 81, 1, 2, 2, 2, 3, 4, 7, 13, 25, 100, 1, 2, 2, 2, 3, 3, 6, 8, 14, 33, 121, 1, 2, 2, 2, 3, 3, 4, 7, 9, 16, 36, 144, 1, 2, 2, 2, 2, 3, 3, 6, 7, 13, 21, 45, 169

Offset

1,3

Links

Table of n, a(n) for n=1..91.

Robert J. McEliece and Herbert Taylor, Covering tori with squares, Journal of Combinatorial Theory, Series A 14.1 (1973): 119-124.

Example

Triangle begins:
1,
1, 4,
1, 3, 9,
1, 2, 4, 16,
1, 2, 3, 7, 25,
1, 2, 3, 4, 9, 36,
1, 2, 2, 3, 7, 14, 49,
1, 2, 2, 3, 4, 8, 16, 64,
1, 2, 2, 3, 3, 6, 9, 22, 81,
1, 2, 2, 2, 3, 4, 7, 13, 25, 100,
1, 2, 2, 2, 3, 3, 6, 8, 14, 33, 121,
1, 2, 2, 2, 3, 3, 4, 7, 9, 16, 36, 144,
1, 2, 2, 2, 2, 3, 3, 6, 7, 13, 21, 45, 169,
...

Crossrefs

Cf. A331145-A331154.

Sequence in context: A176217 A226574 A331154 * A306533 A331146 A196770

Adjacent sequences: A331147 A331148 A331149 * A331151 A331152 A331153

Keyword

nonn,tabl

Author

N. J. A. Sloane, Jan 14 2020

Status

approved